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HomeMy WebLinkAboutCT 01-17; TAMARACK FIVE; GEOTECHNICAL OBSERVATION AND TESTING; 2002-12-04I . I A ORATE: 3320 AIRPORT WAY - LONG BEACH, CALIF. 90806 - PHONE 562/426-7990 -FAX 552/426-1842 SAN DIEGO: 9235 CHESAPEAKE DR. - SAN DIEGO, CALIF. 92123- PHONE 858/974-3691- FAX 858/974-3752 I SOILS ENGINEERING. INC. Consulting Foundation Engineers - , - ., - , . December'4, 2002 - Project No. 02-14570 Manning Homes - I 20151 South West Birch Street, Suite 150 Newport Beach,.California 92660-1713 . Attention: 'Mr. Jim Manning ., . I .Subject: Geotechnical Observation and Testing Proposed Residential, Development (5 Pads & Access Street) 625 Tamarack Avenue Carlsbad, California Reference: Geotechnical Exploration Report prepared by this office under Project No. 01-5421,dated December 13, 2001. Gentlemen.. Submitted herewith is a summary of the observation and testing services provided by this firm I . during rough grading operations within the subject'site. Conclusions relative to the suitability of the grading for the proposed construction and foundation design recommendations for the I- • proposed residential structures are included herein. ' I All fills, cuts, overexcavationS, removals, and processing of, existing ground under the purview I of this report have been, completed under the 'observation of and with selective testing by Associated Soils' Engineering, Inc and is indicated on the enclosed Geotechnical Map, Platel. The earthwork was performed in conformance with our recommendations in the referenced report and the, Grading Code of the City of Carlsbad, County of San Diego,' California. Grading of the subject lots, by Reed Thomas Construction, commenced on November 12, '.2002 and was completed on November 22 2002. .The purpose of the'grading operation was 1 . , . '' . ' '.. '. ' '. • •' . '' ' 4 J to rough grade level building pads for construction of five (5) single-family residences and associated street Recommendations for grading of the site are presented above' The completed earthwork within the five(5) residential budding pads has been reviewed and is considered adequate for the construction now planned 06 the basis of our findings, the following recommendations were prepared in, conformance with generally accepted professional engineering practices and no further warranty is implied nor made. 4 44 1.0 COMPACTION AND TESTING AND OBSERVATIONS' 11 GENERAL 4 This report presents the resuIt of our observation and testing of overexcavation and recompacting during rough grading operations withinthesubject site. :This report includes observation and testing of rough grading operations and the approximate field test locations) as well as, limits of grading within the subject site are delineated on the enclosed Plate 1 The results of laboratory tests are presented in Setion 6.0 of this report - , 1.2 SITE GRADING Within areas that were graded, all existing unsuitable portions of soils were overexcavted to competent material, ps assessed by.-our representatives, prior to placing structural fill The exposed bottom consisted of yellowish brown silt sand and silty sand with clay. The bottom waspbserved by As1ociated Soils Engine6ring, Inc. and is considered adequate for the intended use from 'a geotechnical viewpoint 2.0 TESTING PROCEDURES Field density tests-were performed using the Sand Cone Method (ASTMD 1556), the Drive Cylinder Method (ASTM D 2937), and Nuclear Density Gauge rylthhod (ASTM D 2922). Test results are shown on Table. 1. and approximate locations of the field density tests are-shown on the enclosed Plate 1. The compacted fills.wère tested at the time of placement to verify that the specified moisture content and relative compaction had been achieved At least one in-place density test was 4 . Manning Homes ..• December 4, 2002 Project No.02-14570 - . . Page 2. SOILS ENGINEERING, INC. -4-' I taken for each 1,000 cubic yards of fill placed and/or for ech'2.feet in vertical height of compacted fill. The actual number of tests taken per day varied with the project conditions, I including the number of earthmovers and availability of support equipment I When field density testing indicated a relative compaction of less than 90 percent of ASTM D 1557, the approximate limits of the substandard fill were established. The substandad area was then either reworked moisture conditioned, and recompacted as necessary, or ' substandard materials were removed processed moisture conditioned, and replaced as properly compacted fill Visual classification of earth materials in the field was the basis for determining which dry density value was applicable for a given density test I Fill consisted of blended onsite soils derived from surrounding areas within the subject site Fill materials were placed in lifts restricted to approximately 6 to 8 inches in thickness air I dried or mixed with wet soil, as necessary to achieve near optimum rhoisture conditions, and then compacted by rolling with earth moving equipment on site 30 GROUNDWATER I Groundwater was not encountered during rough grading of the subject site and should not affect the proposed site development provided our recommendations are implemented 4.0 EARTHWORK CONSTRUCTION I Earthwork operations for the subject site have been completed in general accordance with recommendations as provided in the referenced report and in the field during grading Preparation of Existing Ground Deleterious material such as compressible soils, concentrated organic, matter, and miscellaneous debris were 'stripped from the surface and, disposed of offsite, prior to rough grading. Prior to placement of fill within the residential lot areas, the existing ground was overexcavated to a maximum depth of three (3) feet below the existing grade I and at leastthree'(3) feet horizontally, outside the proposed building line.' Manning Homes December 4 2002 4 .,9. . • Project No. 02-14570 Page 3 SOILS ENGINEERING INC I 3. Removal bottomswere scarified to a depth of approximately 6 inches, moisture conditioned and then compacted to attain a minimum relative compaction of 90 i percent. . 0 4. Once excavations and bottom preparation were completed, these areas were I . backfilled with approved Material and. compacted to at least 90 percent reltive comaction and determined to be adequate by probing and/or testing. I .5. . The maximum depth of fill placed under the purview of this. report is 0 approximately three (3) feet. I . 6. All processing of original ground was observed by a representative of ASE. I 5.0 SLOPES .. 0 I 5.1 FILL SLOPES 00 0 0 No fill slopes were constructed, during this portion of rough grading. 0 5.2 CUT SLOPES 0 0 0 No cut slopes were constructed during this portion of rough grading. . 0 6.0 LABORATORY TESTING . I . 6.1 MOISTURE-bENSITYRELATIONS 0 0 0 O . The laboratory maximum dry density and optimum moisture content for the major soil type was determined according to test method ASTM D-1 557-91. -A ,comprehensive list of the laboratory maximum dry density, optimum moisture content, and bearing I value for the rest of the tested soils are can be found in the Appendix. The following . table presents the test results of backfill material utilized during grading onsite. 0 0 0, 00 0 •0 0• 0 £ Manning Homes December 4, 2002 1 Project No. 02-14570 0 Page 4 SOILS ENGINEERING, INC. 0 0, I I 6.2 EXPANSIVE SOILS Expansive:soil conditions have been evaluated for the site. Representative samples of I soil were recovered for classification and expansion testing. Expansion Index (E. 1.) testing was performed in general accordance with 'Standard 18L2, of the Uniform I Building Code' (UBC). The results of the expansion index tests indicate that the, soil underlying the subject building pad exhibit "Very Low" expansion potential as classified in accordance with UBC Table18-l-B:' '. 6.3 SULFATES ' .•' Samples of typical site materials were previously,,tested for sulfate content (Reference I No: 1) and were classified as "Negligible" per, Table 19-A-4- of the 1997 UBC'. Test result's indicate , that sulfate resistant concrete is not necessary for concrete construction. Actual sulfate content varied from 0.006 to 0.039 percent dry weight. I ' . 7.0 FOUNDATION DESIGN I ' 7.1 'BEARING VALUE ' A' dead plus live load allowable soil bearing pressures of 2200 and 2500 pounds per square foot may be used in the design of continupus and spread footings, respectively. Recommended minimum footing width is one foot. The above bearing pressure may be increased by one-third under short term loading from wind or seismic forces. On- site, bearing' soils, meet allowable soil bearing pressure requirements, per the referenced report. 7:2 LATERALPRESSURE 'Pa'ssive earth pressure may be computed as an equivalent fluid having a, density of 250 pounds per cubic foot, to a maximum earth pressure' of. 2,500 pounds per square foot. , An ultHate friction coefficient of 0.4 may , be assumed with'-dead load forces between concrete and the supporting 'soils. 8.0 FOUNDATION CONSTRUCTION Exterior footings should be founded at'a rñinimt3rn depth of 18-inches below the, lowest I ' . adjacent finish soil grade surface from ageotechnical viewpoint. Interior footings may Manning Homes . . December 4, 2002 Project No. O2-1470 . ' Page 5 - SOILS ENGINEERING; INC .. V. have a minimum embedment of 12-inches below the top of the lowest adjacent I -V. ••' concrete slab surface The Project Structural Engineer should determine the ultimate footing dimensions. - I 2. Interior and exteriorslabs should be properly designed for the loading conditions as I well as potential differential movementsbf the slab due to fill loading. The structure details, such as slab thickness, concrete strength, amount and.tye of reinforôements, joint spacing, etc., should be determined by the Project Structural Engineer. I. . 3. The subgrade soils within the slab areas should contain at least optimum moisture content to a depth of 12-inches prior to placement of concrete. , S 4. Soil generated from footing excavations to be used onsite should be compacted to a I V minimum- 90 percent relative compaction whether Jt is to be placed inside the V V V foundation perimeter or in the yard/driveway areas. This material must not, alter positive drainage patterns away from the structural areas and toward the street. • V I All footing excavations should be inspected by the soils engineer. V V • - - - I . V 9.0 PRELIMINARY PAVEMENT DESIGN • Upon completion of rougH grading, R-value sampling and testing was performed on soils I exposed Within,"the street areas. Based . on the assumed cul-de-sac traffic index S requirements, per the City of Carlsbad's Supplemental Standard No. GS-17, and utilizing an I "R"-Value of 58, from Iaboratory testing by this firm,'the recommended preliminary pavement V sections are represented in the table below. S V 1P V V V V V V V Asphaltic Aggregate V Total V St ......e Nj e V CuJ.de-sac V Concrete V V V V Base V V Thicicness V r am Traffic Index (in) (in) (in) I V 'Interior Street'A" 4.5 4.0 '. 40 80 V •, 1.1 •H . V - • Manning Homes December 4, 2002 ,. V _____ - Project No 02-14570 Page 6 V SOILS ENGINEERING, INC V V 1 I Subgrade soils should be properly compacted, smooth, and non-yielding prior to pavement construction. 'The upper 129inches of subgrade soils should be compacted I to a minimum of 95 percent of ASTM Di557-9'l, 'prior to placing of base material, as per the minimum requirements of the City of Carlsbad. Aggregate base 'materials should be either Crushed Aggregate Base, Crushed I Miscellaneous Base, or. Processed Miscellaneous Base conforming to Section 200-2 I . of the Standard Specjfications for Public Works Construction (Greenbook). The materials should be brought to a uniform moiture near optimum moisture content, then compacted to at least 9,5, percent of ASTM Dl 557-91, prior to placing pavement. I , ' Asphaltic concrete materials and.,, construction should conform to Section 203 of the Greenbook. . Pavement section thickness should be increased for areas of heavy vehicular use and for areas where large loads are anticipated.' Should conditions be encountered where Significantly higher moisture contents are present within the subgrade soil, additional overexcavation may be, required to achieve a.firm,' unyielding excavation bottom. 1 . Subgradè drainage is an important factor; 'which enhances pavement performance. Subgrade surface below the flexible pavement structural section should be sloped to I,direct run-off suitable collection points and to prevent ponding. Concrete curbs are required to be underlain by at, least 6 inches of aggregate base, compacted 'as reco,m mended above, by the City of Carlsbad. I '' 10.0 POST GRADING OBSERVATIONS AND TESTING Our firm' should be notified at the appropriate, times in oçder that we may provide the following observation and testing services during the various phases' of post grading construction': I.' . 1. Building Construction Observe footing trenches. when first excavated ,to verify adequate depth and I , competent soil bearing conditions. Manning Homes .: , , . ' December 4, 2002' _-T Project No. 02-14570 .,. ' .' ' ' Page 7 'SOILS ENGINEERING, INC. * I . Re-observe all footing trenches if necessary, if trenches are found to be excavated to inadequate depth and/or found to contain significant slough saturated or ' compressible soils Observe pre-soaking of subgrade soils below floor slab area to verify moisture I content and penetration 2 Retaining Wall Drainage and Backfill I Observe and verify proper installation of backdrain and solid subdrainage outlet systems. Observe and test placement of all wall backfill 3 Concrete Flatwork Construction Observe and tet subgrade soils below, all concrete flatwork areas to verify adequate • compaction and moisture content prior to placing concrete a Garden Walls and Planter-Walls - ,• r .. r I 4. Observe all footing trenches when first excavated to verify adequate depth4 and I competent soil bearing conditions Re-observe all footing trenches, if necessary, if trenches are found to be excavated I to inadequate depth and/or found to contain' significant slough, saturated or compressible soils I 5 Utility Mainline and Lateral Trench Backfills Observe and test placement of all utility mainline and lateral backfills I . 6 Access Construction Street I . Observe and test placement of the base subgrade and asphalt which is to be placed at a later date 4 4. . . &3 • I 7. Re-Grading and/or Completion of Grading Observe and test placement of any fills to be placed above and beyond the grades shown on the grading plan I '4 I 4 Manning Homes December 4-, 20021'I Project No 02-14570 Page 8 SOiLS ENGINEERING INC .4 11.0 OPINiON OF COMPLIANCE AND CLOSURE It is the opinion of this firm that Jhe. grading described in this report was performed in I substantial accordance With the. pdjct plans and specifications. Based on the resilts of our testing and observations, it is our opinion that the compacted fills placed under our I observation and testing as of the date of our last test are acceptable from a geotechnical standpoint for their. intended use. I ' Professional opinions presented in this report are based on our observations, on evaluation of the technical information gathered, on our general undertanding of the earthwork I . construction, and On ourgeneral experience in the geotechniéai field. We do not guarantee theperformance,of. the project in anyrepect, only that. our engineering work and opinions rendered meet the standard of care of our profession at this time I Our field testing services, have been performed in accordance with currently accepted professional engineering practice in the field of geotechnical engineering We make no other warranty, either express or implied. .• . : . I Thank you for the Opportunity of being,bf service to you on this project. FES I Respectfully submitted, ASSOCIATED SOILS ENGINEERING INC. . 3 Lor U ie R. Batë lr4lq~ ID . o . .' Project Geologist .s 'Oo . .. :g; I dward C. (Ted)j ei1 -°' . . ., David T. Hamilton, P. E. Engineering Geologiç Civil Engineer RCE C56590 I LRB/ECR/DTH I ' EncJosures: Tabie1 Field Density Test ResUlts Plate 1'.— Geoteqhnical Map ,. . I Distribution (6) Addressee includes copies for submittal to City of Carlsbad £ Manning Homes ' . December 4, 2002 I Project No.. 02-14570 ' . . . Page 9. SOILS ENGINEERING, INC. TABLE 1. Project Name: Tamarack Avenue - Lots 1-5 Project No: 02-14570 FIELD DENSITY TEST RESULTS Field Relative Approx. Test of (Fill, Test Moisture Dry Density Max. Opt. Moist. Compaction; Test Base, Date No. Type Location (%) (pcf) (pcf) (%) (%) Elevation Native, etc.) 11/12/02 1 N Lot 5 9.4 125:5 131.5 8.5 95 52.3 Fill 11/13/02 •2 S Lot4 9.2 120.0 131;5 8.5 91 52.5 it If 3 N Lot5 10.0 122.5 131.5 8.5 93 53.3 11/14/02 4 N Lot 8.7 122.8 131.5 8.5 93 51.5 5 N Lot 5 10.6 121.3 131.5 8.5 92 52.5 6 N Lot 2 9.4 124.3 .131.5 8.5 95 50.6 11/15/02' 7 N Lot 10.6 121.3 131.5 8.5 92 50.0 8 S Lot 5 9.9 123.7 131.5 8.5 94 F. G. 9 N Lot 4 8.1- 125.2 131.5 8.5 95 10 N Lot 75 1202 1315 85 91 " II 11 S . Lot 2 8.1 1209 131.5 :8 5 : 92 12 N : Lot 1 8.7 . 118:•2 131.5 8.5 90 If . '• " 'I 11/21/02 13 N : Street ' 10.6 • 116.8 : 128.5 : ;9•5 : 91 : : 49.0 14 N:: Lot 6 9•4 : '115.8 • 128.5 95 • 90 52.0 II: 11/22/02 15 N Lot 8.7 120.5 :128.5 9.5 •• 94 • F. G. If 16 N Lot • 10.0 118.0 128.5 9.5 • 92 . 17 N Street • 8.1 121.8 128.5 • 9.5 95 • 48.0 NOTES: N Denotes tests performed by Nuclear Gauge (ASTM D2922). : S Denotes tests performed by Sand Cone (ASTM D1556-91). : F. G. Denotes Finish Grade. ' : • T-1 SOILS ENGINEERING, INC. : :